Wind power generation involves using wind turbines to generate electricity from the kinetic energy of moving air. This mature technology has achieved good economic performance and is ready for widespread implementation.
Many of the negative perceptions about wind power are based on early-generation wind turbines. Modern turbines have technological improvements to control low-voltage ride-through and output/ramp rate and provide volt-ampere-reactive support. With these capabilities, turbines can remain connected to the grid during voltage disturbances, mitigate their draw on the grid’s reactive power resources, and maintain continuous real-time communications and data exchange with the control area operator.
Wind farms in the United States generated an estimated 70,760 GWh of electricity in 2009, which represented about 1.2 percent of the U.S. electricity supply (EIA, 2010c [Renewable Energy Consumption and Electricity Preliminary Statistics]). The U.S. wind power capacity spans 34 states and totaled 33.5 GW of capacity in 2009 (EIA, 2010d). At the end of 2009, there were approximately 300 GW of proposed capacity additions in transmission interconnections queues, nearly nine times current installed capacity, although not all of these projects are likely to be installed (Wiser et al., 2010). The state of Texas is currently home to two of the largest wind farms in the world—Roscoe Wind Farm (780MW) and Horse Hollow Wind Energy Center (735MW).
China has the largest industry and market for mini- and micro-wind generators in the world. From 1983 to 2009, 609,039 small- and medium-sized turbines were produced in China. In 2009, 34 manufacturers produced 100,318 sets, of which 47,020 were exported (CWEA, 2010). China set initial goals of 5 GW of installed wind capacity by 2010, and 30 GW by 2020 (NDRC, 2007). The 2010 goal was quickly revised to 20 GW, and China still reached the goal a year earlier than planned (2009 instead of 2010) and more than doubled its installed capacity from 2008 to 2009 (12.2 GW to 25.8 GW) (CWEA, 2010). The latter goal of 30 GW will likely be reached by the end of 2010, and the revised 2020 goal of 100 GW installed capacity may be further revised to 150 GW. To put this in perspective, global installed capacity as of 2009 was 158 GW (GWEC, 2010), and China would annually be installing capacity that is greater than total installed capacity of the UK, Portugal, and Denmark (as of 2009). To achieve this goal, China will have to expand its production capabilities to produce not only 1.5 MW units, but also 3 to 5 MW units. Figure 3-1 shows how wind deployment has evolved over the years in the United States, China, and the rest of the world.
One aspect of wind energy projects that must be taken into consideration is the capacity factor, that is, the measure of a wind turbine farm’s productivity. In the United States, the capacity factor increased from 22 percent for projects